API

Adyen is an enterprise fintech platform offering "one platform for payments, data, and financial products," enabling large businesses to accept payments, send payouts, and launch financial services through a single API.

Algolia is an AI-powered search and discovery API platform providing "one AI retrieval platform" for agentic, generative, and traditional search, recommendations, and personalization experiences.

Apigee is Google Cloud's API management platform that helps organizations design, secure, publish, and analyze APIs at scale.

Elastic is the company behind Elasticsearch, a distributed RESTful search and analytics engine, offering unified solutions for AI-powered search, observability, and security built on the same data platform.

Kong describes itself as "The AI Connectivity Company," providing the connectivity layer for the agentic era — securely connecting, governing, and monetizing APIs and AI tokens across any model or cloud, via products like Kong Gateway and Kong Konnect.

MuleSoft Anypoint Platform is Salesforce's unified iPaaS and full-lifecycle API management solution, letting organizations securely design, build, deploy, secure, and manage APIs and integrations at scale in one platform.

Plaid calls itself "the world's largest financial data network," enabling companies to connect to financial institutions and build fintech solutions on top of verified account and transaction data.

Postmark is a transactional email API and SMTP service built for developers, focused on fast, reliable delivery, and has delivered billions of emails since 2010.

RapidAPI (per its own documentation) is "the world's largest API hub," used by millions of developers to discover, test, and connect to thousands of third-party APIs using a single API key, while also letting API providers distribute and monetize their APIs.

SendGrid, now operated under Twilio's platform, is an email API and SMTP service providing email solutions for transactional email at scale and marketing email campaigns.

Stripe describes itself as "financial infrastructure to grow your revenue," letting businesses accept payments, offer financial services, and implement custom revenue models — from your first transaction to your billionth.

Twilio positions itself as "the platform for conversations in the AI era," providing programmable communications APIs (messaging, voice, email via SendGrid, video, authentication) that let companies build customer conversations across channels.

WorkOS is an API platform that lets software applications quickly add enterprise-ready authentication and user management, including SSO, directory sync, and audit logs, without building identity infrastructure from scratch.